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Halios Seaforth vs Marathon GSAR

Both are dive watches in the upper tier. In short: the Marathon GSAR takes more water (300m) — both are fine for swimming, but it has more margin if you dive. The Halios Seaforth is automatic, 200m water resistance, 41mm, sapphire crystal; the Marathon GSAR is automatic, 300m water resistance, 41mm, sapphire crystal.

Last verified 2026-06-27 · specs from manufacturer data · tier = price band, confirm the live price at the retailer

SpecHalios SeaforthMarathon GSAR
MovementAutomaticAutomatic
Water resistance200m300m
Case size41mm41mm
Crystalsapphiresapphire
StyleDiveDive
Price tierUpperUpper

Which should you buy?

The Marathon GSAR takes more water (300m) — both are fine for swimming, but it has more margin if you dive.

Where to buy

Halios SeaforthSee price on AmazonCheck price

Marathon GSARSee price on AmazonCheck price

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FAQ

What's the difference between the Halios Seaforth and the Marathon GSAR?
Both are dive watches in the upper tier. The Halios Seaforth is automatic, 200m water resistance, 41mm, sapphire crystal; the Marathon GSAR is automatic, 300m water resistance, 41mm, sapphire crystal.

Which has better water resistance, the Halios Seaforth or the Marathon GSAR?
The Marathon GSAR, rated 300m, versus 200m on the other. Pick 100m or higher for swimming and 200m+ for diving.

Which is better value, the Halios Seaforth or the Marathon GSAR?
Both sit in the upper tier, so it comes down to movement, water resistance and case size — see the spec table above.

Citing these specs? Go ahead — manufacturer data, last verified 2026-06-27. Copy a ready-made reference:

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